A heterojunction is an interface region formed by a contact of two different semiconductor materials. According to the conductivity types of different semiconductor materials, the heterojunction can be divided into homogeneous heterojunction (P-p junction or N-n junction) and heterotypic heterojunction (P-n or p-N). A heterostructure can be formed by multilayer heterojunctions. The heterostructure can be used in semiconductor element and semiconductor device.